Beta 2-microglobulin studies in endemic Balkan nephropathy.

The diagnosis of BEN and its differentiation from other chronic interstitial nephropathies are difficult because of the insidious onset as well as nonspecific morphological changes in the kidney. Early diagnosis of this disease is by clinical and laboratory findings which have not been universally accepted. This study was designed to determine if the frequency of increased urinary beta 2-microglobulin (U beta 2m) in village populations at risk to develop BEN was significantly higher than that seen in a control population. Individuals in the two population samples were classified in one of three categories: healthy, suspect or diseased. There were 23 individuals who met the criteria for the clinical diagnosis of BEN. Twenty (87%) of these had one or more positive tests for increased U beta 2m. The prevalence of kidney disease in the endemic village population sample was 13.4 times that for the control village population sample. The data show that the healthy individuals living in a village where BEN is endemic have 6.4 times greater chance of having tubular proteinuria than those living in a control area. The coincidence of the finding of U beta 2m in the urine of 87% of those sick with BEN and in 37 of the 342 (10.8%) people judged to be free of kidney disease suggests that a positive U beta 2m test is an early indicator of exposure to a nephrotoxic agent.